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Professor Jagadis Ch under Bose 



[May 29, 



pending on racial characteristics. One might expect that the tongue 

 of the Celt would be far more excitable than that of the stolid Anglo- 

 Saxon. In any case the superiority of man has to be established on 

 foundations more secure than sensibility ; for the plant Biophytum, 

 I find, is eight times more sensitive to an electrical current than a 

 human being. With regard to the stimulus of induction shock, 

 Mimosa is ten times as sensitive. As with the animal so also with 

 the plant, the effect of stimulus is additive, that is to say, effective 

 stimulation is determined not only by the intensity, but also by the 

 duration of application. In fact I have been able to establish in 

 plants a strictly quantitative relation as regards the additive effect of 

 sub-minimal stimulus, which is, that the effective excitation is equal to- 



Fig. 5. — Diagrammatic Kepresextation of Automatic Plant-Recorder, 

 Petiole of Mimosa, attached by thread to one arm of lever L ; writing 

 index W traces on smoked glass plate G the responsive fall and recovery 

 of leaf. P, primary, and S, secondary, of induction coil. Exciting 

 induction shock passes through the plant by electrodes E, E', A, accumu- 

 lator. C, clockwork for regulating duration of tetanizing shock. Primary 

 circuit of coil completed by plunging rod R dipping into cup of mercury M. 



individual intensity of stimulus multiplied by the numher of repetitions. 

 In order that successive stimulations may be uniform, we have to assure 

 ourselves that the duration of the tetanizing shock is maintained 

 absolutely constant. This I am able to secure by means of the 

 special device of automatic stimulator. The results*^ of experiments 

 to be presently described appeared so astonishing, that for many 

 reasons it became highly desiraljle to remove completely all elements 



